Intubation:
For decades, a daily used traditional metal blade laryngoscope was commonly employed to place an endotracheal tube into a person's trachea. However, a blade laryngoscope presents significant patient risks. These risks include dental injury, airway tissue injury, and further injury to patient's with a neck injury caused by neck manipulation during intubation. A further limitation is the limited ability or inability to visualize vocal cord for intubation, if a full dose of a muscle relaxant was not given to increase the opening a patient's mouth for insertion of a metal laryngoscope blade. The muscle relaxant can have additional detrimental side effects. Multiple attempts of intubation by a traditional metal laryngoscope also significantly increase the risk of morbidity and mortality.
The many prior art devices have been used in a routine or difficult endotracheal intubation cases. They can be divided roughly into four categories: traditional and video laryngoscopy, supraglottic airway device, fiber optic scope intubation and others.
In the first category, the traditional Miller and Macintosh metal laryngoscopy which has been used for many decades. Currently, there are many video laryngoscopes in clinical use, such as the Glidescope, McGrath, Airtraq, C-Mac, Berci-Kaplan DCI, Pentax Airway Scope, Truview EVO, and APA video laryngoscopy. These video laryngoscopy devices rely on obtaining an indirect view of the epiglottis and glottis inlet during intubation. However, their basic blade design is based on a traditional Macintosh metal blade plus a visualization capability that can incorporate a viewing screen. Their blade's shape and curve are rigid and very similar to traditional Macintosh metal laryngoscopy blade in shape and curvature. They carry the same disadvantage of the traditional metal blade. Their hard rigid preformed prominent curve makes them difficulty to insert and can easily cause damage to a patient's airway. Therefor their use require a full dose of a muscle relaxant medication to open the patient's mouth wide. A variety of types of trauma, airway bleeding, heavy secretion, or a patient's injury requires intubation in an unusual position, such as in a car wreck or with a cervical spine injury which is better to be intubated without moving their head or body position, all those clinical situation can make direct or indirect visual observation of the vocal cords very difficult if not impossible by traditional metal laryngoscopes or by video laryngoscopes. Another disadvantage of video laryngoscopes is that they are expensive to manufacture.
The second category includes supraglottic airway devices including different types of laryngeal mask airway, brief as LMA, I-gel, intubation laryngeal mask airway, air-Qsp, laryngeal tube and others. These devices are mainly made of plastic materials and designed as a supraglottic airway for a patient's ventilation in routine and emergency cases. One drawback of this type device is that the tip of LMA can fold during insertion or can be compressed and twisted by surrounding tissues to block ventilation. And the cuff can exert excessive pressure to the tissues in one area and have not enough sealing pressure in another area causing the air leaking and possibility of aspiration of esophageal gastric content. In a newly designed LMA supreme, the rigid pre-formed curve can cause tissue damage and the preformed curve and fixed length from the curve to the distal end makes it very difficult for the device to fit the varying anatomy of each patient. These problems can be greatly exaggerated in mechanical ventilation scenarios, especially in an obese patient.
The second device category claims the capability of placement of an endotracheal tube through the device. Intubation laryngeal mask airway, brief as ILMA, was especially designed for blind intubation without visualization of the laryngeal inlet or vocal cords. However, the ILMA has a metal handle with a very prominent curved region making it difficult to insert into a patient's mouth. Second, the ILMA relies on precisely positioning and alignment of the epiglottis with the recessed epiglottis elevation bar. This precise position is required so that the epiglottis elevation bar can raise the epiglottis out of the way of an advancing endotracheal tube. Such precise position is often hard to achieve. Otherwise the operator has to rock the device back and forth to try to achieve the correct alignment. This device movement can cause a lot of damage to a patient's airway tissues. Further, the endotracheal tube can become lodged against the edge of laryngeal inlet or vocal cords due to the angle of the endotracheal tube entering the glottis opening. So ILMA requires a specially made and expensive endotracheal tube. Often times this tube needs to be changed to a regular endotracheal tube if the patient needs mechanical ventilation after surgery. In addition, ILMA still has the same problems as other types of LMA due to their basic design concepts. In one prior art, U.S. Pat. No. 8,128,071, optical fibers were added to gain visualization of the laryngeal anatomy, but this device still suffers from the limitations stated above.
For the third category of devices, the use of a flexible fiber-optic scope intubation of the trachea has been used in medical practice for decades which allows for placement of an endotracheal tube with minimal manipulation of the patients airway. While this technique had been considered the gold standard in cases with awake patient intubation, this technique is time consuming and not suitable in emergency situations and the use of this type of device requires significant skill and training
The fourth type of prior art devices incorporates guides for intubation. U.S. Pat. No. 4,832,020, “Tracheal Intubation Guide,” U.S. Pat. No. 6,672,305 in 1989, “Shallow Throat Orotracheal Intubation Guide” and RE39,508 E, 2007 “Blind Orolaryngeal and Oroesophageal Guiding Aiming Device” disclose a tracheal intubation guide which sits above the glottis. However, such a design does not assurance stable alignment of the device with respect to the laryngeal opening. Therefore, an endotracheal tube can be misguided and cause miss-intubation and laryngeal trauma. In another prior art, U.S. Pat. No. 7,040,312, 2006, “Peri-laryngeal Oral Airway” it discloses an oral airway that can be used to guide an endotracheal tube into a trachea by axially advancing the endotracheal tube through a gap defined by the material forming the grate of the wedge-shaped housing. But this depends on where the wedge shaped housing is inserted. Therefore, intended result is very difficult to be achieved.
Positive Pressure Mechanical Ventilation:
It is standard practice of requiring endotracheal intubation on a patent when positive mechanical ventilation is planned. Using a supraglottic airway device for spontaneous ventilation has been widely accepted, but not for mechanical ventilation. All currently used supraglottic airway devices can result significantly air leaking out patient's mouth during positive pressure mechanic ventilation even when an associated balloon is inflated to a high pressure which can cause damage to the airway tissues, and air insufflation into patient's stomach. And in comparison to traditional endotracheal tube, various supraglottic airway devices need a higher inspiration pressure to achieve the same tidal volume of ventilation. However, the higher inspiration pressure can cause gastric contents regurgitation and pulmonary aspiration and at same time the higher inspiration pressure is hard to achieve due to air leakage.
The objectives of the various embodiments of this invention are to minimize and mitigate the complication, co-morbidity, and to achieve more effective intubation and ventilation.